The protection of crops from weeds and other vegetation which inhibit crop growth is a constantly recurring problem in agriculture. To help combat this problem researchers in the field of synthetic chemistry have produced an extensive variety of chemicals and chemical formulations effective in the control of such unwanted growth. Chemical herbicides of many types have been disclosed in the literature and a large number are in commercial use.
Unfortunately, many of such herbicides will exhibit phototoxicity to the desired crop as well as to the weeds sought to be controlled. Thus, there is a long-standing need for selective herbicides which will not adversely affect the crop plants when applied at herbicidally effective levels.
Isoxaflutole [5-cyclopropyl-4-(2-methylsulfonyl-4-trifluoromethyl)benzoylisoxazole] is disclosed in European Patent Publication No. EP-0527036 and is a highly effective herbicide in corn. used pre-emergence or pre-plant incorporated [see for example Vrabel et al., Proc. North Cent. Weed Sci. Soc. Volume 49. pages 49-50 (1994); and Luscombe et al. Proc. Br. Crop Prot. Conf. Weeds. Volume 1. pages 35-42 (1995)]. At elevated dose rates however, or when applied post-emergence a problem can exist that corn may be damaged by this compound. European Patent Publication No. EP-0487357 describes. interalia. 3-ester-4-benzoylisoxazoles having activity against a variety of weed species. In particular, EP-0487357 describes ethyl 5-cyclopropyl-4-(2-methylsulfonyl-4-trifluoromethyl)benzoylisoxazole-3-car boxylate (as Compound BB).
It has now been discovered that such compounds will effectively control a broad range of weeds typically associated with corn without exhibiting any substantial phytotoxic effects on the corn itself.